The central role of places in which physical activity is done is now widely recognized, so it is important to measure both activity and its location. We will develop a Physical Activity and Location Measurement System (PALMS) comprised of an integrated suite of hardware and software that supports real-time capture and subsequent analyses of data on physical activity and energy expenditure (PAEE) from a geospatial perspective. Capability for ecological momentary assessment (EMA) of psychosocial factors related to PAEE context will also be included. No measurement approach exists that is capable of simultaneously and objectively collecting PAEE by combined heart rate and motion (HR+M) and location by Global Positioning Systems (GPS) data. These objective measures will provide significant advantages over currently-available self-reports to help understand relationships between PAEE, the environment, and health-related factors. This project will be performed by an interdisciplinary group of researchers with expertise in physical activity and energy expenditure measurement, active living research, software engineering, wireless sensor networks, cell phone technologies, GPS and geographic information systems (GIS) research and data modeling. The project will occur in four phases: PHASE I (12 mo.): Specify, build and bench test the software architecture that supports data collection from both an HR+M monitor and a highly accurate GPS device as well as a cell phone. Develop data-server and web-server software including new application program interfaces as well as methods to integrate into existing well established GIS systems (e.g. ArcGIS). PHASE II (12 mo.): Perform usability testing of the portable tool, refine the system and then use it to capture a minimum of 45 person-weeks of combined PAEE, GPS and EMA data among a multiethnic sample (n=45) of adolescents (age 12-20), adults (age 21-59) and older adults (age 60+). PHASE III (12 mo.): Use data captured in PHASE II to develop methods of data modeling and analysis appropriate to PAEE and geospatial research. Further improve the tool and software for use in Phase IV and develop User Guide and Web Tutorial for Researchers. PHASE IV (12 mo.): Field test the entire system (PAEE, GPS, EMA data collection, supporting server, and web software) in free-living adolescents, adults and older adults (n=45;min. 45 person-weeks) and test the utility of the system as a support to research on geospatial aspects of PAEE.